Exhaust-fan



(No Model.)

J. E. GREEN.

EXHAUST FAN.

No. 499,673. Patented June 13, 1893.

%ZWEM EK IJV'I/ZJVIOJZ UNITED STATES PATENT Enron,

JAMES E. GREEN, OF ST. LOUIS, MISSOURI.

EXHAUST-FAN.

SPECIFIQATION' forming part of Letters Patent No. 499,673, dated June13, 1893.

Application filed October 31, 1890- Serial No. 369,940- (No model.)

To all whom it may concern.-

Be it known that I, J AMES E. GREEN, of St. Louis, Missouri, have made anew and useful Improvement in Exhaust-Fans, of which the following is afull, clear, and exact description.

The present fan, while having a general resemblance to fans hitherto inuse, is distinguished by the shape of its blades, and by theirarrangement with relation to the airinlet of the fan, and to the casing,substantially as is hereinafter described and claimed, aided by theannexed drawings, making part of this specification, in which- Figure 1is a view showing the fan in side elevation and the casing in section;Fig.2 an edge elevation of the fan, and Fig. 3 a crosssection of one ofthe blades.

The same letters of reference denote the same parts.

A represents the fan, and B the casing.

0 represents the shaft to which the fan is attached. The construction isof the ordinary character saving as it is modified or supplemented bythe improvement under considera: tion; and only that portion of theconstruction is exhibited which is required for an understanding of theimprovement. The fan, in the present instance, has four blades, a, a, a,a, but any suitable number can be used. The blades are attached to thearms, a, a, a, a, respectively, which in turn connect with the hub, 00The blades are mainly flat and, in width, extend across the width of thecasing, the side edges, a a coming as near as is practicable to thesides, I), b, respectively, of the casing, but in place of the bladebeing flat throughout its entire width its side portions are curvedforward, in the direction of the movement of the fan in its rotation,substantially as described.

An additional feature of the improvement is the arrangement of the fanblades with reference to the air-inlet of the fan. Instead of the bladesbeing arranged radially they are adjusted respectively in planes which,when projected, intersect at right angles radial lines drawn through thecenter of the fan, substantially as shown in Fig. 1. In practice,

the points through which said planes pass are, preferably, about onethird, generally speaking, the distance from the center of the fan tothe rim of its casing. The blades extend inward to opposite theperiphery of the air-inlet, and their supporting arms, a, are attachedto the blades respectively at the center of the inner end thereof, andthe blades at the inner end thereof are substantially square,substantially as shown, thereby minimizing the surface presented to theair in the central part of the fan.

Another feature is the relation of the fanblades to the rim, Z), of thecasing above the outlet, 12 from the casing. The casing, in the respectreferred to, is, at b drawn inward so as to leave only sufficient roomfor the blades in their rotation to pass. In practice one eighth of aninch, at the point named, suffices.

In operation the fan is driven in the customary manner. The inlet to thecasing is at 6 and the direction of the movement of the fan, and of theair current caused by the rotation of the fan, is indicated by thearrows 0:, 00. By reason of the fan blades being curved at the sidesthereof as described the current produced by the fan is less liable toescape between the sides of the blades and the sides of the casing, and,on the other hand, and by reason of the flatness of the main portion ofthe blades, the air is not concentrated opposite the central portion ofthe blade, but is distributed evenly in front of it. Owing to thedescribed tangential arrangement of the fan blades the blades actadvantageously upon the current in drawing it effectively through theinlet, 17 into the casing, and then in impelling it through the casingand discharging it through the outlet b The blades thus arranged act tothrow the current outward in the direction of the rim of the casing aswell as forward in the direction of the outlet from the casing, andthere is no back-action through the inlet, and as a practical result thecapacity of the fan is large in proportion. to the area of its bladesand the rate at which the fan is driven. The efficiency of the fan isfurther increased in consequence of the described contraction of thecasing at the outlet therefrom. Much less of the current is carriedaround again with the fan than is the case when considerable space, ashitherto has occurred in the construction of fans, exists between thecasing and the outermost point reached by the fan-blades in theirrotation. Each of the above described features of the improvement isvaluableirrespective of the presence of the other described features.But either two, or all, of them, in combination, are still more useful,and the best results are obtained When all of them are united in oneconstruction, substantially as shown.

I claim- An exhaust fan combining in its construction the casing, theshaft, and the fan, said casing having the described air inlet at thecenter of the side thereof, and the blades of

